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Modeling and Control Law Optimization Design of Starting Process of the Three-Shaft Turboshaft Engine 1

Asia-Pacific International Symposium on Aerospace Technology (APISAT)

作者： Yan, Dongxu Tang, Hailong Chen, Min Zhang, Jiyuan Dong, Pengcheng Zhou, Junhao Beihang Univ Res Inst Aeroengine Beijing 102206 Peoples R China Beihang Univ Sch Energy & Power Engn Beijing 100191 Peoples R China AeroEngine Acad China Beijing 101304 Peoples R China China Gas Turbine Estab Chengdu 621703 Peoples R China

ISBN: (数字)9789819740109

ISBN: (纸本)9789819740123;9789819740109;9789819740093

The starting process of the three-shaft turboshaft engine is a complex dynamic process. Compared to the single-shaft turboshaft engine, the low-pressure compressor of the three-shaft turboshaft engine will occur the surge failures during the starting process. To ensure the compressor has sufficient surge margin, it is necessary to bleed air between the high-pressure compressor and the low-pressure compressor, which results in energy waste and efficiency decline. Thus, it is necessary to balance the safe operation and performance loss of the engine during the dynamic operation. In this paper, a starting model based on the component characteristics for the three-shaft turboshaft engine is established on the SIMULINK platform. The sequential quadratic programming (SQP) method is used to optimize the control law of the starting process considering several safety limit parameters. The optimized starting control law has a 16.2% reduction in starting time at the standard sea level atmosphere. Compared to the original control law, the bleed air of the starting process is reduced by 7.2%.

关键词： Three-shaft Turboshaft Engine Low-state Component Characteristics Extrapolation sequential quadratic programming Control Law Optimization Design of Starting Process

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quadratic programming solver for structural optimisation using SQP algorithm

Quadratic programming solver for structural optimisation usi...

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2nd International Conference on Engineering Computational Technology/5th International Conference on Computational Structures Technology

作者： Horowitz, B Afonso, SMB Univ Fed Pernambuco Dept Civil Engn BR-50740 Recife PE Brazil

The dual quadratic programming algorithm of Goldfarb and Idnani is implemented as a solver for a sequential quadratic programming algorithm. Initially the algorithm is briefly described. As the algorithm requires the inverse of the Cholesky factor of the Hessian matrix at each iteration a procedure is presented to directly obtain a matrix that multiplied by its transpose gives the BFGS update of the Hessian. A procedure is then presented to triangularise the updated factor using two series of Givens rotations. In order to increase efficiency a 'warm start' strategy is proposed whereby the choice of constraints to enter the active set is based on information of previous SQP iterations. Finally two examples are given to demonstrate the efficiency and robustness of the implementation. (C) 2002 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved.

关键词： optimisation structural design mathematical programming sequential quadratic programming quadratic programming finite elements

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Structural optimization of cylinder-crown integrated hydraulic press with hemispherical hydraulic cylinder 11

Structural optimization of cylinder-crown integrated hydraul...

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11th International Conference on Technology of Plasticity (ICTP)

作者： Zhang, Weiwei Wang, Xiaosong Wang, Zongren Yuan, Shijian Harbin Inst Technol Sch Mat Sci & Engn Harbin 150090 Peoples R China

Cylinder-crown integrated hydraulic press is an innovative press. The hemispherical hydraulic cylinder also functions as a main portion of crown. Compared with the conventional hydraulic press in which cylinder mounted in the crown, the thickness of hemispherical hydraulic cylinder could be much thinner and the crown section modulus could be much higher under the same application condition. As a result, the material strength capacity is better utilized. Based on sequential quadratic programming, structural optimization of hemispherical hydraulic cylinder for weight reduction has been carried out within the range of constraints including strength and stiffness conditions. Compared with the initial design, a lighter structure with weight reduction 7% and acceptable stress distribution has been obtained. Considering the advantages of cylinder-crown integrated hydraulic press, according to its optimization design, a 6300KN prototype hydraulic press has been manufactured. (C) 2014 The Authors. Published by Elsevier Ltd.

关键词： Cylinder-crown integrated hydraulic press Optimization design sequential quadratic programming

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A Bayesian Approach to Collaborative Optimization with Application to Tailless Aircraft Range Maximization

A Bayesian Approach to Collaborative Optimization with Appli...

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AIAA Aviation Forum and Exposition

作者： de Becdelievre, Jean Kroo, Ilan Stanford Univ Dept Aeronaut & Astronaut Stanford CA 94305 USA

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

Collaborative Optimization is a two-level design optimization architecture that allows the solution of multidisciplinary problems as a series of single-disciplinary problems with very little infrastructure overhead. It can be a very practical option in cases where practitioners do not have a fully coupled multidisciplinary optimizers at hand, but have access to multiple single-disciplinary optimizers. However, in its current form the method can require a large number of single-disciplinary evaluations and be slow to converge. In this work, we propose an improvement to the original method. We show how, at each iteration of the Collaborative Optimization framework, orthogonal projections on the feasible set of every discipline are performed. Mimicking the Bayesian Optimization framework, we propose to learn probabilistic representations of the feasible sets with the projection information, and use them to choose the next sample point in a principled manner. We also show that ensembles of Lipshitz neural networks are well performing probabilistic representations in this case. The approach is applied to a tailless aircraft range maximization problem.

关键词： Tailless Aircraft Feedforward Neural Network Bayesian Optimization Bayesian Approach Lift Distribution Lift Coefficient Surrogate Model Probability Distribution sequential quadratic programming Multidisciplinary Design Optimization

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Network Controlled D2D Communications: Licensed or Unlicensed Spectrum?

Network Controlled D2D Communications: Licensed or Unlicense...

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IEEE International Conference on Communications (IEEE ICC)

作者： Wu, Fanyi Zhang, Hongliang Di, Boya Wu, Jianjun Song, Lingyang Peking Univ Sch Elect Engn & Comp Sci Beijing Peoples R China

ISBN: (纸本)9781538680889

In this paper, we consider a device-to-device (D2D) communications underlaying cellular network where Long Term Evolution (LTE) and D2D users are allowed to communicate over both licensed and unlicensed bands for spectrum efficiency improvement. LTE users utilize spectrum orthogonally and share it with D2D users. To maximize the total throughput of this D2D system, we leverage stochastic geometry to derive the throughput for each kind of users by modeling the deployment of users as Poisson point processes (PPPs), and investigate the mode selection problem for D2D users. Since the problem is NP-hard, we propose a sequential quadratic programming (SQP) based algorithm to obtain the corresponding suboptimal solutions. Theoretically, we evaluate the system performance by analyzing the throughput regions. Simulation results validate the accuracy of the geometric analysis and verify the effectiveness of the proposed algorithm.

关键词： Device-to-device unlicensed communications mode selection stochastic geometry sequential quadratic programming

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Surrogate Model Based Aerodynamic Shape Optimization of a Hydrogen Powered Aircraft

Surrogate Model Based Aerodynamic Shape Optimization of a Hy...

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AIAA Aviation Forum

作者： Kiely, Michael Agarwal, Ramesh K. Washington Univ St Louis St Louis MO 63130 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

This paper describes both the low and high fidelity methods used in implementation of machine learning based optimization techniques for aerodynamic shape optimization of hydrogen powered commercial aircraft. Using vortex lattice method based aerodynamic performance estimations in conjunction with empirical solvers used to estimate an arbitrarily generated aircraft's overall structural weight and drag, a Bayesian optimization algorithm is applied to optimize the wing to maximize the aircraft's overall range. This method was applied to a test case of the Boeing 737-800 where it was seen to predict the planform shape of the real world wing with a high degree of accuracy. This methodology is then applied to the design of transonic supercritical airfoils in which the airfoil is parameterized and optimized to reduce drag at a specified lift coefficient. The resultant airfoils are seen to closely resemble modern supercritical airfoils and reduce the drag significantly. Lastly a method of airfoil surrogate modelling using convolutional neural networks to predict aerodynamic performance of airfoils at a fraction of the computational cost is examined. This method is seen to provide highly accurate estimates for the drag coefficient of airfoils, however is seen to fall short of being able to fully optimize the airfoils. Ultimately the previously described methodologies are all used in conjunction to create a computer program which is able to fully optimize the geometry and airfoil distribution of a wing with high degree of accuracy at the maximum possible computational efficiency.

关键词： Surrogate Model Hydrogen Powered Aircraft Aerodynamic Shape Optimization Supercritical Airfoils Convolutional Neural Network Bayesian Optimization Aerodynamic Performance Vortex Lattice Method sequential quadratic programming Computer Programs

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Optimization on steady-state cruise for a hypersonic vehicle 33

Optimization on steady-state cruise for a hypersonic vehicle

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33rd Chinese Control Conference (CCC)

作者： Liu, Xing Wang, Yongji Liu, Lei Huang, Jian Huazhong Univ Sci & Technol Schlool Automat Wuhan 430074 Peoples R China

ISBN: (纸本)9781479947249

This paper concentrates on optimization of the steady-state cruise for a hypersonic vehicle. The steady-state cruise is a state with constant altitude and velocity during the flight. The ratio of fuel consumption to the range over a given period of time is defined as the fuel rate, which is the objective of this fuel optimized problem in this work. The optimal steady-state cruise is determined by minimizing the fuel rate with multi-constraints including boundary constraints of states and path constraints. Since this work needs to find the global solution satisfying the nonlinear constraints, we can apply particle swarm optimization(PSO) combined with the sequential quadratic programming(SQP) to find the optimal solution. Thus, this strategy takes the advantage of intelligent optimization algorithms with global search ability and SQP with high precision and handled constraint ability. A demonstration example results show good performance of fuel savings on the nonlinear model of the hypersonic vehicle.

关键词： Hypersonic vehicle Steady-state cruise Fuel optimization Particle swarm optimization sequential quadratic programming

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An inexact NE/SQP method for solving the nonlinear complementarity problem

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Computational Optimization and Applications 1992年第1期1卷 67-91页

作者： Gabriel, Steven A. Pang, Jong-Shi Department of Mathematical Sciences The Johns Hopkins University Baltimore 21218 MD United States

In this paper, we present an extension to the NE/SQP method;the latter is a robust algorithm that we proposed for solving the nonlinear complementarity problem in an earlier article. In this extended version of NE/SQP, instead of exactly solving the quadratic program subproblems, approximate solutions are generated via an inexact *** a proper choice for this rule, this inexact method is shown to inherit the same convergence properties of the original NE/SQP method. In addition to developing the convergence theory for the inexact method, we also present numerical results of the algorithm tested on two problems of varying size. © 1992 Kluwer Academic Publishers.

关键词： equilibrium programming linear complementarity problem matrix splitting Nonlinear complementarity problem nonsmooth equations sequential quadratic programming

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Reliability and optimum design of structures with magnesium alloys

Reliability and optimum design of structures with magnesium ...

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2nd International Conference on Platform Science and Technology for Advanced Magnesium Alloys

作者： Kogiso, N Matunaga, S Furuya, H Osaka Prefecture Univ Dept Aerosp Engn Sakai Osaka 5998531 Japan Tokyo Inst Technol Dept Mech & Aerosp Engn Meguro Ku Tokyo 1528552 Japan Tokyo Inst Technol Dept Built Environm Midori Ku Yokohama Kanagawa 2268502 Japan

ISBN: (纸本)0878499148

This study is concerned with the reliability-based optimum design of a stiffened panel made of magnesium alloy subject to natural frequency. The panel is regarded as failure when the natural frequency is lower than an allowable limit. Since the lowest mode may be shifted due to variations of random variables, the panel failure is modeled as a series system consisting of several vibration modes. The mode reliability is evaluated by the first order reliability method (FORM), where the Young's modulus and panel dimensions have variations. In order to avoid the reliabiltiy overestimation, the tunneling algorithm modified to the FORM is utilized. The system reliability is approximated by Ditlevsen's upper bound. The total weight is minimized subject to the system reliability constraints in terms of the panel dimensions. Through numerical calculations, the reliability-based optimum design is demonstrated to be different from the deterministic optimum design. The results show the importance of considering variations of the random variables for the safety in designing a magnesium alloy structure.

关键词： magnesium alloy stiffened panel natural frequency reliability-based optimization structural reliability first order reliability method mode tracking sequential quadratic programming

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Discretization Error Guided Optimal Mesh Adaptation in One-dimensional Steady Problems

Discretization Error Guided Optimal Mesh Adaptation in One-d...

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AIAA Aviation Forum

作者： Carvalho, Eduardo de Oliveira Moura, Rodrigo Costa de Castro da Silva, Andre Fernando Aeronaut Inst Technol ITA Dept Aerodynam Praca Marechal Eduardo Gomes 50 BR-12228900 Sao Jose Dos Campos SP Brazil

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

When solving differential equations, one must often use spatial discretization. However, this process introduces errors that are mesh dependent. Thus, improving solution quality while saving computational resources requires adequate spatial resolution. One way of doing so is to treat this issue as an optimization problem that targets the reduction of discretization error. The current work presents an approach to mesh optimization using r-adaptation and the adjoint method for one-dimensional steady equations. The two equations selected to display this methodology are the heat equation with a forcing term and the viscous burgers equation. The discretization method is a second-order finite differences scheme. The results present a substantial reduction in discretization error when the optimized meshes are employed.

关键词： Inhomogeneous Heat Equation Finite Difference Scheme sequential quadratic programming Space Domain Computing Dirichlet Boundary Condition Implicit Euler Method MATLAB Kinematic Viscosity Mathematical Models

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